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Abstract: The concept “critical flux” allows for a relatively new operation optimization of ultrafiltration (UF) in fouling control strategies. The present studies mostly pay attention to colloids, organic solution and surface fresh water, which are of a less complex chemistry than that of seawater. In this work, “critical flux” was applied into the field of seawater desalination to investigate the utility of this concept for dealing with UF membrane fouling. Firstly, the nature flux mode, a new measurement for the critical flux, was proposed for UF in treating seawater and compared favorably with other measurements such as constant flux mode and constant pressure mode. Secondly, the definition (strong form J cs and weak form J cw) of critical flux for UF of seawater was evaluated to make sure whether or not the perfect operating condition (without UF fouling) is in existence. Thirdly, the effects of sub- and super-critical flux operations using different operating modes on the extent of membrane fouling were investigated by measuring hydraulic resistance. Moreover, a brief analysis of the economic feasibility of sub-/super-critical flux operations was covered. The results showed that the highest E p was yielded when operating in constant pressure mode with higher TMP under super-critical flux conditions, while the lowest E p in constant/nature flux mode with higher permeate flux under sub-critical flux conditions. When operating in constant/nature flux modes, lower E p was achieved under sub-critical flux conditions than under super-critical flux conditions. [Copyright &y& Elsevier]

Membrane distillation technology has been studied thoroughly in China and since the beginning of the 1980s it has developed quickly. This article provides an introduction to the basic concept of membrane distillation and includes details of its application in the metallurgical industry. Membrane processes related to membrane distillation are also briefly discussed, as is the future development of this technology. [Copyright &y& Elsevier]

Abstract: This work deals with a novel thin-film-composite membrane based on layer-by-layer self-assembly of polyelectrolytes onto an interfacially polymerized polyamide membrane for dehydration of ethylene glycol by pervaporation. Polyethyleneimine and poly(acrylic acid) were used as the polycations and polyanions, respectively. Compared to conventionally used microporous substrates for polyelectrolyte layer-by-layer buildup, the use of interfacially polymerized polyamide membrane as a substrate would significantly reduce the number of polyelectrolyte bilayers needed to form a permselective pervaporation membrane. For instance, the resulting membranes showed a good permselectivity flux with only two to three bilayers of the polyelectrolytes; a permeation flux of 0.4kg/(m2 h) and a separation factor of 340 were obtained at 40°C for a feed water concentration of 3wt% using a membrane with three polyelectrolyte bilayers. For the separation of water from ethylene glycol using the polyelectrolyte/polyamide composite membranes, both the solution thermodynamics and the membrane permeability were favorable toward water enrichment in the permeate. [Copyright &y& Elsevier]

Triethanolamine (TEA) has been broadly used as the organic amine conditioning agent to modify the workability of cement-based materials. However, the effect of TEA on the structure and property of porous silicate cement membranes has not been reported. In this paper, TEA was applied to study its effect on parameters of porous silicate cement membranes based on the preparation method combining freeze casting and heat-dry curing, because it is easy to form complexes with cement particles. The effect and acting mechanism of TEA on porous silicate cement membranes were researched using a series of characterizations and molecular dynamics (MD) simulation. Results showed that TEA significantly improved the performance of porous silicate cement membranes. The addition of TEA changed the pore morphology of porous silicate cement membranes from lamellar structures to cellular structures, with mesoporous size distribution focusing on 2.5–4.5 nm at TEA doping ratio of 0.16 wt%. The oil-water separation performance could reach up to 99.6 %. Through comprehensive comparison, the porous silicate cement membrane with 1.0 wt% TEA showed better holistic preponderance of oil-water separation and permeation flux. Quantum chemistry calculation and MD simulation were used to briefly explain the influence of TEA on phase transformation. MD showed that adding TEA changed the morphology and structure of ice crystals. The percentage of the Ih structure significantly increased from 53 % to 86 % after adding TEA. This study might expand the application of TEA in other aspects and enlighten relevant workers in new experimental designs. [Display omitted] • TEA noticeably changed the pore morphology form lamellar to cellular structures. • Cement membranes doped TEA showed excellent separation performance and stability. • Effects of TEA on crystals were analyzed via quantum chemistry and MD simulation. [ABSTRACT FROM AUTHOR]

Acid‐alkaline amphoteric water electrolysis (AAA‐WE) can produce green hydrogen under reduced voltage and energy consumption. However, its conflicting demands on ion exchange membranes to have both high ionic conductivity and barrier properties between H+ and OH− have thwarted its own development. Here, the preparation of anisotropic polybenzimidazole (PBI) ion‐solvating membrane (ISM) made of hundreds of 28 nm thick nano‐sheets (PBI‐aNS) from gel state PBI (PBI‐Gel) membranes via 2D‐polarized/1D shrinking process, in which loosely packed multi‐layer PBI nano‐fibrous assemblies are shrunken into hundreds of layers of tight 28 nm thick nano‐sheets, is reported. The resulting PBI‐aNS membranes possess excellent dual‐ion conductivity (H+ and OH−), good acid/alkali barrier capability, and robust mechanical properties. Acid‐alkaline amphoteric water electrolysis (AAA‐WE) using PBI‐aNS separators achieves a high current density of 1 A cm−2 at 1.4 V (with iR‐correction) under a voltage increasing rate of 6.1 mV h−1. This newly designed ISM will lead to new possibilities for the development of next‐generation water electrolysis devices with improved green hydrogen production efficiencies. [ABSTRACT FROM AUTHOR]

Preparation of porous cement-based materials via freeze casting is a process with great potential. However, freeze-drying and steam curing complicate the preparation process and increase the preparation period. To simplify the process, heat-dry curing was used for replacing freeze-drying and steam curing during operation. The new preparation method combined freeze casting and heat-dry curing possesses characteristics of low-energy, simplicity, and time-saving. Compared with the traditional preparation method of porous cement-based materials, the novel preparation process can shorten preparation time by at least 16 % and retrench energy consumption by at least 18 %. As the improvement condition, temperature of heat-drying curing has great influence on the structure and performance of the samples. Therefore, it is of great significance to discuss the relationship between heat-dry temperatures and structural parameters by SEM, N 2 -adsorption/desorption, TG, and ATR-FTIR. Lamellar pores of membranes can be easier observed at low temperatures than that at 100 °C. The separation performance of oil-water is generally improved with the increase of temperature. Meanwhile, the molecular dynamics simulation was operated to illustrate the reaction mechanism of hydration with three temperatures. This study probably provides more theoretical basis for expanding the application of porous silicate cement membranes. [Display omitted] • Novel coupled method simplifies the fabricating process complexity of cement-based samples. • Influences of heat-dry curing temperatures on porous silicate cement membranes are discussed. • Silicate cement membranes own excellent permeation, oil-water separation and mechanical strengths. • Influences of heat-dry curing temperatures are illustrated by using molecular dynamics. [ABSTRACT FROM AUTHOR]

Preparation of porous cement-based materials via freeze casting is a process with great potential. However, freeze-drying and steam curing complicate the preparation process and increase the preparation period. To simplify the process, heat-dry curing was used for replacing freeze-drying and steam curing during operation. The new preparation method combined freeze casting and heat-dry curing possesses characteristics of low-energy, simplicity, and time-saving. Compared with the traditional preparation method of porous cement-based materials, the novel preparation process can shorten preparation time by at least 16 % and retrench energy consumption by at least 18 %. As the improvement condition, temperature of heat-drying curing has great influence on the structure and performance of the samples. Therefore, it is of great significance to discuss the relationship between heat-dry temperatures and structural parameters by SEM, N 2 -adsorption/desorption, TG, and ATR-FTIR. Lamellar pores of membranes can be easier observed at low temperatures than that at 100 °C. The separation performance of oil-water is generally improved with the increase of temperature. Meanwhile, the molecular dynamics simulation was operated to illustrate the reaction mechanism of hydration with three temperatures. This study probably provides more theoretical basis for expanding the application of porous silicate cement membranes. [Display omitted] • Novel coupled method simplifies the fabricating process complexity of cement-based samples. • Influences of heat-dry curing temperatures on porous silicate cement membranes are discussed. • Silicate cement membranes own excellent permeation, oil-water separation and mechanical strengths. • Influences of heat-dry curing temperatures are illustrated by using molecular dynamics. [ABSTRACT FROM AUTHOR]

Electrodialysis, an efficient and environmental friendly separation technology, plays a significant role in water treatment. In order to reveal ion transfer mechanism and predict electrodialysis behavior, a mathematical model for steady transport of a binary electrolyte during the desalination process was developed. The Nernst–Planck, electroneutrality equations, and other hydrodynamic equations were coupled and solved with appropriate boundary conditions using the finite element method. This model is capable to predict the local ion concentration, electric potential, and ion flux in a rectangular electrodialysis unit. The effects of voltage drop (0.4–1.0 V), inlet velocity (0.03–0.06 m/s), and initial feed concentration (500–700 mol/m3) are investigated, which could provide valuable guidance for electrodialysis operation in the practical project. Moreover, this model is validated by comparing its simulation result with experimental data of electrodialysis, and it could predict the desalination of saline water accurately. Ion transfer modeling provides an effective way to study the transfer mechanism, estimate the effects of various parameters conveniently, and realize the target‐oriented operation optimization. [ABSTRACT FROM AUTHOR]

Porous silicate cement membranes (PSCMs) fabricated by the freeze casting method show great potential to be utilized in seawater pretreatment, fermentation broth separation, and industrial wastewater treatment due to its merit of high-temperature resistance, low-cost, and hierarchically ordered porous structures, while the freeze casting method is complex and time-consuming. In this work, a combination of freeze casting and heat-dry curing was initially applied to generate PSCMs. The preparation periods of PSCMs could be shortened by simplifying preparation processes and reducing curing time. The resulting membranes presented double-layer structures, containing a nucleation zone (N-zone) with dense structures and a stability zone (S-zone) with lamellar pore structures. The X-ray diffraction pattern of membranes displayed the mixed hexagonal and rhombohedral structures. This novel method could save more than half of energy consumption compared with the traditional preparation technology of silicate cement samples. The membranes with a mesopore size of 3.794 nm showed high permeation performance with pure water flux reaching 207.23 L m−2 h−1 under 0.15 MPa and room temperature. The separation efficiency of oil-water was 78.05% under operating pressure of 0.05 MPa. Molecular dynamics simulation was applied to narrate the microscopic process of transformation during heat-dry curing, and obtained a good similarity of consequences between the computational method simulation and experimental operation. [Display omitted] • Freeze casting combined with heat-dry curing to fabricate porous silicate cement membrane. • Freeze drying and steam curing were replaced using heat-dry curing. • Porous silicate cement membranes showed lamellar porous structures. • Molecular dynamics simulation was used to elucidate the hydration process of heat-dry curing. [ABSTRACT FROM AUTHOR]

Novel high boron removal thin film composite (TFC) membranes with semi-interpenetrating networks were fabricated by interfacial polymerization (IP) with m-phenylenediamine (MPD) and 1,3,5-benzenetricarbonyl trichloride (TMC). The polyisobutylene (PIB) was added to the organic phase prior to IP. The membranes were characterized by attenuated total reflectance Fourier transform infrared spectrometry (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and the zeta potential and contact angle analysis. The results of this study demonstrate that the novel TFC membrane exhibited superior separation performance at a relatively low concentration of PIB (0.30%, m/v). As the concentration of the interpenetrating PIB in the membrane increased, the membrane morphology changed distinctly. Furthermore, the permeability coefficient of boron decreased from 20.84 to 3.26, and the rejection of boron increased from 81.36% to 93.12%. [ABSTRACT FROM AUTHOR]

A series of self-supporting and substrate-supporting polysulfone (PSf) ultrafiltration (UF) membranes was fabricated using various substrates including glass plates, polypropylene random plates (PPR) and three kinds of non-woven fabrics (NWFs) via a typical phase inversion technique. Effects of the substrate hydrophilicity and structure on the membrane characteristics, morphology, separation and anti-fouling performance were systematically investigated. For self-supporting membranes, compared to glass plates, PPR facilitated more porous membranes and higher pure water permeability ( L p ), permeation flux as well as anti-fouling property. NWFs density played an important role in the separation performance of the NWFs-supporting membranes. The resulting membrane with loosest NWFs exhibited an ultrahigh L p of approximate 13,572 L/m 2 h per MPa without any sacrifice of rejection, which significantly outperformed almost all the PSf membranes with L p of 1000–7000 L/m 2 h per MPa in literature. In addition, fouling filtration tests were performed in dead-end mode using humic acids solution followed by physical washing. More reversible rather than irreversible fouling was found in the NWFs-supporting membranes, especially for the membrane with loosest NWFs, indicating an improved anti-fouling property. This work endows the conventional PSf membranes with the outstanding properties such as ultrafast water transport and high flux recovery in an efficient and facile way. [ABSTRACT FROM AUTHOR]

The separation of magnesium and lithium is the key issue of preparation of pure lithium product due to their similar chemical property. Thermodynamic analysis was conducted on the removal of magnesium from lithium chloride solutions with phosphate precipitation method. The thermodynamic equilibrium diagrams of Mg 2 + - PO 4 3 - - H 2 O, Li + - Mg 2 + - PO 4 3 - - H 2 O and Li + - Mg 2 + - NH 4 + - PO 4 3 - - H 2 O systems at 298 K were established, separately. The effect of process parameters on the removal of magnesium was also investigated. The results revealed that the existence of Li + was not beneficial to the removal of magnesium, and the precipitation method of MgNH 4 PO 4 performed better than that of Mg 3 (PO 4 ) 2 for the separation of magnesium from lithium chloride solutions. The equilibrium concentration of magnesium decreased with the increase in total concentration of NH 4 + and the decrease in concentration of Li + . With the precipitation method of MgNH 4 PO 4 , there are four regions of stable solid phase in the pH range of 4.5–13.0 in lithium chloride solutions containing 1 mol/L Li + , 0.03 mol/L NH 4 + , 0.01 mol/L Mg 2 + and 0.03 mol/L PO 4 3 - , which are MgHPO 4 (5.9 < pH < 6.6), MgNH 4 PO 4 (6.6 < pH < 9.6), Mg(OH) 2 (10.0 < pH < 13.0) and Li 3 PO 4 (6.6 < pH < 1.3), respectively. The verification experiment results showed that the concentration of magnesium can be reduced to 0.011 g/L from a feed solution containing 14.95 g/L (∼1 mol/L) Li 2 O and 0.45 g/L (∼0.02 mol/L) Mg 2+ by adding 0.025 mol/L ( NH 4 ) 3 PO 4 · 3 H 2 O at pH 8 and 25 °C, while the concentration of residual phosphorus in purified solution was only 0.004 g/L, which was consistent with the thermodynamic analysis. [ABSTRACT FROM AUTHOR]

The cosolvent-assisted interfacial polymerization (CAIP) has garnered significant attention due to its capacity to easily and effectively modify the performance of polyamide (PA) reverse osmosis (RO) membranes. To gain deeper understanding of the mechanism of a specific type of cosolvents on the IP reaction, namely N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N,N-dimethylpropionamide (DMPr) were used as aqueous-phase cosolvents to systematically investigate their effects on the membrane structures and properties under different conditions. Amide cosolvents in the aqueous phase facilitated the diffusion of the amine monomer and the formation of nanovoids within the PA layer as the C-chain length of amides increased. When 1,2-dichloroethane was also included in the organic phase, the extent of the two-phase miscible zone was further increased with its assistance, which contributed to generating the larger nanovoids within the layer, thicker PA layer and extensive exterior PA layers, as well as significantly enhancing the water permeability and selectivity of membranes. Importantly, this study successfully prepared high-performance RO membranes with multilayer nanovoid structures in situ by introducing cosolvents in the IP reaction with permeability up to 2.26 L·m−2·h−1·bar−1, providing theoretical and experimental bases for further enrichment of CAIP. [Display omitted] • Exploring the effects of different amides on the diffusion of amine monomers. • Longer chain DMPr contributes to the formation of multilayered nanovoid structures. • Correlating amine monomer diffusion rate with PA layer evolution. • TFC a-o -DMPr shows water permeability of 2.26 LMH/bar and NaCl rejection of 98.38 %. [ABSTRACT FROM AUTHOR]

The robust correlation between the performance of thin-film composite (TFC) reverse osmosis membranes and the polyamide (PA) active layer determines the necessity of precise design of the PA layer, and this regulation primarily involves the surface morphology and internal characteristics of the PA layer. In this study, we fabricated honeycomb Turing structure or nanovoid-rich TFC series membranes using polar/nonpolar organic phase additives. Characterization and simulation results confirmed that the enhancement of membrane performance relied more on the abundant nanovoids within the PA layer rather than the ordered honeycomb lattice surface. Notably, the TFC-nDCE membrane with multilayer nanovoids exhibited an approximately 89 % improvement in water permeability while maintaining satisfactory salt rejection (98.29 %). We emphasized the significant role of nanovoids in the diffusion process of amine monomers and investigated the potential relationship between nanovoids and the degree of surface cross-linking. Building upon this, a new insight into the formation of nanovoids induced by PA anisotropic growth was presented through a careful analysis of the amine monomer diffusion rate and the morphological evolution of nanovoids. The structure-property relationship between internal structures, surface morphologies, and performances was systematically and thoroughly investigated, pointing out the direction for the rational design of TFC membranes. [Display omitted] • Revealed effects of nanovoids on the water/salt flow in honeycomb Turing PA layer. • Impacts of nanovoids on the physicochemical structure of PA layer were emphasized. • New insights on the anisotropic growth of PA were provided. [ABSTRACT FROM AUTHOR]

For nanofiltration (NF) membranes, constructing the interlayer between the substrate and polyamide (PA) layer could balance the trade-off effect between the selectivity and permeability. However, the influencing mechanism of the interlayer to the PA layer is mostly indirect, and how to regulate the physicochemical properties of the PA layer to improve the membrane property remains to be investigated. In this study, porous Zn-TCPP nanosheets with active reaction sites were used to construct interlayer and directly participated in interfacial polymerization (IP) reaction through the edge COOH of nanosheets reacting with piperazine (PIP) to further regulate PA layer physicochemical properties. Controlling the amount of nanosheets involved in the reaction, NF membranes with striated Turing structures, higher negatively charged surface and larger effective filtration area were obtained. The NF membrane permeability with Zn-TCPP interlayer was significantly improved by 123 % while the Cl−/ SO 4 2 − selectivity was greatly enhanced to 72.69, meanwhile it showed excellent performance stability. This study presents a new perspective that the interlayer can modulate the NF membrane physicochemical properties to improve its performance by directly participating in the IP reaction. [Display omitted] • Porous Zn-TCPP interlayer directly participates in the IP reaction via peripheral carboxyl groups. • Zn-TCPP interlayer reduces the pore size of substrate and inhibits the downward growth of polyamide. • Surface morphology of NF membranes is changed, and hydrophilicity and electronegativity are enhanced. • Zn-TCPP interlayer improves the selectivity of NF membrane for mono-/di-anions. [ABSTRACT FROM AUTHOR]

A new configuration of electrodeionisation with a bipolar membrane (EDI-BP) with a segment electrode was proposed for the treatment of simulated dilute Ni 2 + -containing wastewater. The feasibility of EDI-BP was analysed and experimentally validated, and its current density distribution was studied simultaneously. The results showed that the stack allows the removal of nickel and sulphate anions nearly completely from the 30 mg/L Ni 2 + -containing wastewater. Under the experimental conditions, Ni 2 + -free diluate and a 27-times concentrated solution (820 ± 50 mg/L) can be obtained. The current density distribution of the stack is uneven, which is reflected by the following order of the resistances of the resins, Dowex 650C and Dowex 550A, with different ionic forms: Ni 2 + > Na + > H + and SO 4 2 − > Cl − > OH − , respectively. [ABSTRACT FROM AUTHOR]

Abstract: The effects of pH, feed concentration and operation pressure on the recovery of vanadium from acid leach solution of stone coal using nanofiltration membrane technology were investigated. The rejection and permeate flux of vanadium with two kinds of membranes in nanofiltration process were also studied. After pre-treatment of leach solution to remove calcium by the addition of sodium carbonate, the vanadium in the final concentrated solution can be up to 30g/L from 1.429g/L in the feed under the optimum conditions of pH6–6.5 and operation pressure of 2069kPa at room temperature during nanofiltration process with the rejection of vanadium more than 95%. The final concentrated solution can be directly used to produce the V2O5 by traditional method, and the permeate stream can be recycled to leaching. The conceptual flow sheet for the extraction of vanadium from acid leach solution using nanofiltration membrane has been developed. [Copyright &y& Elsevier]

Abstract: Pilot-scale experiments were carried out on a nanofiltration (NF)–seawater reverse osmosis (SWRO) integrated membrane system (IMS) to evaluate scaling potential on NF and SWRO membrane surface using a kind of loosen NF membrane and costal seawater. The effect of NF permeate recovery (R NF ) increasing on the occurrence of scaling in the NF and SWRO module was investigated in term of concentration polarization modulus (CP) of scalant ions, Stiff and Davis Stability Index (S&DSI), as well as Supersaturation Index (SI) of CaCO3 and CaSO4. The results show that the salt rejection by the loosen NF module is only about 10%, while the rejection of SO4 2− is higher than 95%; S&DSI is always less than zero, indicating that CaCO3 scaling could not form on the NF membrane surface when R NF was less than 35%. is much higher than ; and at R NF of higher than 30%, SI of CaSO4 on NF membrane surface increased gradually higher than 1.0, which indicated that CaSO4 scale is more apt to form on the NF membrane surface than CaCO3 at that NF permeate recovery. This scaling sequence in the loose NF module was different from that in traditional SWRO desalination processes. [Copyright &y& Elsevier]

Abstract: Cogeneration for power and desalination could not only improve the economic benefit of the power plant, but also afford the high quality water to solve the freshwater shortage. Considering the demand of power and water, a detailed mathematical model of the cogeneration system targeting the minimum total annual cost (TAC), which includes the power plant, multistage flash (MSF) and reverse osmosis (RO), is proposed and described as a mixed integer nonlinear programming (MINLP) problem. The modified genetic algorithm (MGA) with mixed coding is put forward to solve the model developed by us. A case study, which is supposed to supply 250MW of power and 12,000m3/h of water for Huangdao District of Qingdao City, is analyzed in order to illustrate the model capabilities. The results show that the operation pattern of the cogeneration system could be varied in terms of the water demand. When the water demand is lower than 8000m3/h, the combination of power plant associated with MSF is adopted and the condensing-extraction steam turbine is selected. When the water demand of water is higher than 8000m3/h, the tri-combination of power plant, MSF and RO is the optimal choice, in which back pressure steam turbine is selected. [Copyright &y& Elsevier]

A facile one-step surface modification strategy was developed to zwitterionize polyamide based thin-film composite (PA-TFC) nanofiltration membranes via in-situ ring-opening reactions with a series of cyclic chemical reagents, including γ-butyrolactone(γ-BL), δ-valerolactone(δ-VL) and ε-caprolactone(ε-CL), 1,3-propanesultone (1,3-PS) and 1,4-butanesultone (1,4-BS). The impact of chemical reactivity, ring size, and length of formed zwitterionic chains of these modifiers on the surface properties and nanofiltration performance were comprehensively investigated. It was found that the loading density of the zwitterionic chains was mainly determined by internal ring strain of the cyclic modifying reagents, while the chemistry effect on water permeability was mainly reflected in the surface hydrophilic nature of the formed membranes. Loading of zwitterionic chains with medium length sulfonic acids tends to increase surface hydrophilicity and membrane water permeability while loading of short carboxylate zwitterionic chains tends to increase the retention selectivity of membranes. NF membranes with long and soft hydrophobic –C 4 H 8 - and –C 5 H 10 - hydrocarbon chains tend to have less flux and retention selectivity. Owing to these competing factors, the NF membranes modified by 1,4-BS exhibited the greatest water permeability (10.9 L/m2⋅h⋅bar) with high retention selectivity (MgCl 2 /NaCl ratio: 4.2 and Na 2 SO 4 /NaCl ratio: 3.1) while the NF membranes modified by γ-BL showed the greatest retention selectivity (MgCl 2 /NaCl ratio: 5.5 and Na 2 SO 4 /NaCl ratio: 4.2). All the zwitterionic membrane possessed high Na 2 SO 4 and MgSO 4 rejections (97–99%) and enhanced anti-fouling performance with 100% recovery capability. This work provided a facile and straightforward way to prepare zwitterionic membranes with significantly improved water permeation and retention selectivity of divalent/monovalent ions. Direct zwitterionization of NF membranes could realize a simultaneous improvement of retention selectivity and water permeation via in-situ ring-opening reactions. [Display omitted] • Direct zwitterionization of NF membranes realized by ring-opening reactions. • Loading density was mainly controlled by ring strain energy of cyclic reagents. • Water permeation change increase came mainly from increased surface hydrophilicity. • Retention selectivity and water flux could be simultaneously increased. • Remarkably high divalent salt rejection ratios and 100% flux recovery achieved. [ABSTRACT FROM AUTHOR]

Tight ultra-filtration (TUF) membranes were constructed by in situ growing zinc imidazole frameworks micro-crystalline leaves (ZIF-L) in polyethylene imine (PEI) and polydopamine (PDA) deposit layers on porous polyethylene (PE) substrates. The effects of preparation conditions on the surface physical and chemical structures as well as on the dye/salt separation performance of the formed TUF membranes were systematically investigated. By inserting selective water permeation channels and increasing contacting surface areas, in situ-grown ZIF-L arrays tightly cross-linked in the coating matrix greatly increased water permeation without trading off dye/salt retention selectivity. The morphology of the included ZIF-L particles could be varied by adjusting the ligand/Zn molar ratio (α) in the preparation processes. Optimized PDA-PEI/ZIF-L@PE TUF membranes containing ZIF-L of cross-cross block morphology showed very high pure water permeability of 180 ± 20 L·m−2·h−1·bar−1 (LMHB) and retention selectivity (S CR/Na2SO4 and S MB/Na2SO4) of 267 and 43, respectively, as well as excellent stability and anti-fouling properties. [Display omitted] • Lower cost-based TUF membranes were prepared for effective dye/salt separation. • In situ-grown ZIF-L increased water flux without losing dye retention selectivity. • PEI and PDA coating greatly enhanced the stability of ZIF-L in water. • Morphology of ZIF-L was tuned for improving membrane performance. • Protonation of the -NH- groups increased positive charge and water flux. [ABSTRACT FROM AUTHOR]

Organic solvent forward osmosis (OSFO) is a newly developing technology for recovering the organic solvent and concentrating substances. The commercial polyethylene (PE) battery separator is the ideal support for OSFO owing to the low structural parameter, resistance for organic solvents, commercially available and simple preparation process. A novel thin-film nanocomposite (TFN) membrane for OSFO was fabricated on the dopamine (DA)-modified PE support by adding α-cyclodextrin (α-CD) in the polyamide (PA) layer. The inclusion complexes (MPD@α-CD) formed by host-guest chemistry enhanced the stability of the membrane. Because of the Janus path and molecular sieving effect of α-CD, the TFN membrane exhibited superior permeability and selectivity among the recent reports. Moreover, the TFN membrane showed high rejection of Rhodamine B and Oxytetracycline, so it had great potential for solutes concentration. Herein, this work broadens the application of eco-friendly α-CD in membrane field and improves the PE composite membrane for OSFO process. [Display omitted] • PE battery separator can withstand organic solvents and reduce ICP. • α-Cyclodextrin slows down the diffusion of MPD through host guest reactions with MPD. • The ethanol flux of TFN membrane reaches at 3.92 L·m−2·h−1. • TFN membrane show excellent stability and great potential for concentration solutes in organic solution. [ABSTRACT FROM AUTHOR]

Composting is a process of converting potentially harmful organic matter into harmless organic fertilizer through microbial fermentation. This process enables the rational use of resources and represents an embraced technology marked with sustainable development features. Hindering ammonia emissions during composting is vital, as ammonia is a valuable resource and harmful if emitted excessively. Polytetrafluoroethylene (PTFE) membranes are often used as functional covering membranes to prevent ammonia produced by composting from releasing due to its hydrophobicity. However, they are susceptible to oily aerosols in oily composting, which affects microbial decomposition in aerobic composting. Thus, the development of amphiphobic PTFE membrane is necessary and meaningful. For the amphiphobic PTFE membrane, an important issue is the amphiphobic stability of the membrane, especially in the special alkaline environment of composting. Herein, we suggest the use of the polymer to wrap around nanoparticles and PTFE membrane fibers to prepare stable amphiphobic membranes as functional covering membranes for oil-containing composting. Poly(methyl-3,3,3-trifluoropropylsiloxane) (PTFPMS) and 1H, 1H, 2H, 2H-perfluorodecyltrichlorosilane (PFTS) entangled with each other and then wrapped the nanoparticles and membrane fibers to form stable amphiphobic membranes with high roughness and low surface energy. The prepared membrane had high liquid repellency to water (～152.8°), diiodomethane (～127.5°), and n-hexadecane (～127.0°). This membrane also possessed a high anti-oil fouling. Moreover, the membrane amphiphobicity exhibited a high stability. This is attributed to the stable fixation of nanoparticles on PTFE membrane fibers with PFTS/PTFPMS. Therefore, the amphiphobicity of the membrane was not affected by ammonia. As for the ammonia filtration efficiency, the amphiphobic membrane had a filtration efficiency of 77.4 % within 10 min, an increase of 6.8 % compared to the PTFE membrane, demonstrating the potential of the membrane we developed toward hindering ammonia emission. This work provides a new way of developing high-performance membrane for the oily composting process. [Display omitted] • An amphiphobic PTFE membrane was developed for oily composting. • The membrane repelled both water and oil highly because of low surface energy and high roughness. • The polymer wrapped the nanoparticles and membrane fibers to form a stable amphiphobic PTFE membrane. • The developed membrane exhibited a good ability for hindering ammonia emission. [ABSTRACT FROM AUTHOR]

The development of reverse osmosis (RO) membranes with both high permeability and selectivity is a key goal for RO technology, the leading water treatment technology. This work presents a simple and cost-effective method for improving RO membrane performance obviously via introducing a hydrophobic small molecule, benzoic acid (BA), in the polyamide (PA) separation layer. The introduction of BA is achieved by adding it in the oil phase of the interfacial polymerization technology because of its oil solubility, which is pretty simple. The hydrophobicity and self-assembly characteristic of BA could establish hydrophobic microenvironments within the PA separation layer. The hydrophobicity of this microenvironment can reduce the number of hydrogen bonds between water molecules, accelerating the rapid transport of water and thereby enhancing membrane performance. Concurrently, BA as a small molecule could moderately increase the space between PA chains and thus enlarge the free volume of hydrophobic microenvironment region, which is also in favour of the improvement of membrane flux. The as-developed RO membrane possessed both high rejection rate (with a NaCl rejection rate of 98.9 %) and high flux (91.7 L m−2 h−1) under the brackish water testing condition, surpassing the performance of many previously reported membranes, and noticeably, a flux increase of 113 % was achieved by utilizing BA. Besides, the performance showed a good long-term stability. It is worth mentioning that small molecules are generally purchasable and cheap, which is beneficial to the large-scale production. This work showcased the great potential of hydrophobic small molecules in improving PA water treatment membrane performance, paving the way for diverse small molecules to develop PA water treatment membrane with both high permeability and selectivity. [Display omitted] • A strategy to improve the RO membrane performance by using small molecule to construct hydrophobic microenvironment in the separation layer was proposed. • The free volume of separation layer was enlarged by the small molecule (benzoic acid). • The microenvironment constructed by benzoic acid had evident hydrophobic characteristic. • The membrane flux was improved obviously by 113 % to 91.7 L m−2 h−1 and meanwhile a high NaCl rejection of 98.9 % was maintained. [ABSTRACT FROM AUTHOR]

Abstract: A novel process of solvent extraction for separation of molybdenum (Mo) from ammonium tungstate (W) solution containing high content of Mo was developed using a mixture of tri-alkyl phosphine oxide (TRPO) and tributyl phosphate (TBP) as extractant and hydrogen peroxide (H2O2) as complex agent. The extraction process was studied to optimize various parameters such as extractant concentration, contact time, temperature, dosage of H2O2, and initial pH of aqueous solution. The extraction isotherms for Mo were also plotted. The results indicated that the addition of TBP in organic not only improved phase separation both in extraction and stripping, but also increased the extraction of Mo and decreased the extraction of tungsten (W), and hence improved the separation properties of Mo/W. The extraction of Mo was higher than 63% and the separation coefficient β Mo/W was larger than 80 under optimal conditions. The loading capacity was determined to be 12.33g/L Mo and 9.44g/L Mo at equilibrium pH of 1.58 and 2.05, respectively. The further separation of W and Mo was realized in stripping process. NH4HCO3 was the optimum stripping agent because of its good phase separation, effective stripping of Mo and high Mo/W selectivity. The effects of contact time, temperature, concentration of stripping agent and O/A ratio on the stripping were investigated with NH4HCO3. The stripping of Mo reached 89% in comparison to that of W that is less than 16% after one contact. The concentration of Mo in strip liquor was 70–90g/L and the mass ratio of Mo/WO3 in strip liquor was larger than 26 at an O/A ratio of 8:1–10:1 using 0.8–1.0mol/L NH4HCO3. The stripped organic was directly reused to extraction. A principle flowsheet of the recovery of Mo and W was developed. [Copyright &y& Elsevier]

The aim of this work has been to study the influence of modified hole-extraction layers on the performance of organic solar cells (OSCs) based on blends of poly (3-hexylthiophene) and [6,6]-phenyl-C61-butyric acid methyl ester. The hole-extraction layers consist of poly (3,4-ethylene dioxythiophene):polystyrene sulfonic acid (PEDOT:PSS) doped with different concentrations of bromine. Compared with pristine OSC without adding bromine to the hole-extraction layer, the bromine-doped OSCs show a 49% increase in the power conversion efficiency (from 2.12 to 3.16%), which could be attributed to the increase of electrical and optical properties of PEDOT:PSS films after the addition of bromine. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 50: 125-128, 2012 [ABSTRACT FROM AUTHOR]

Abstract: One of the common problems for the production of organic acid using electrodialysis technology is the relative high energy consumption due to their weak dissociated ability. Enlightened by our previous work [Journal of Membrane Science 341 (2009) 246–251 and Journal of Membrane Science 366 (2011) 266–271] in which the ion exchange resin were filled in the product compartments, a conducting spacer instead of the traditional non-conducting spacer was adopted for the convenience of the operation to facilitate ion transportation during the production process of the tartaric acid by the bipolar membrane electrodialysis technology. Herein, the cell voltage, the current efficiency and the energy consumption were investigated and compared before and after the use of the conductive spacers, respectively. Furthermore, the process economics were all evaluated and compared with the traditional methods. The experimental results showed that the conductive spacer can effectively facilitate the transport of the hydrogen ions in the product compartment and then effectively decrease the energy consumption of the tartaric acid production by the process. But, on the other hand, the simultaneous effects resulting from the hydrogen ion short circuit, including the reduced producing rate and current efficiency, also took place. [Copyright &y& Elsevier]

Abstract: In this study, a novel process to modify thin-film-composite polyamide membrane was developed. It involved surface treatment of the polyamide membrane by chlorine, followed by supramolecular assembly of chitosan on the membrane surface. While the original polyamide membrane was negatively charged, the surface modification led to a charge reversal due to skin layer of chitosanium in the resulting polyamide/chitosan composite membrane. The polyamide/chitosan (PA/CS) composite membrane was shown to perform better than the original polyamide membrane. The parameters involved in the chlorination of polyamide (e.g., chlorination time and chlorine concentration) and supramolecular assembly of chitosan (e.g., concentration and deposition time) on the membrane surface were investigated. The following conditions for membrane modification were found to be appropriate: NaClO concentration 200mg/L, chlorination time 2–5min, and chitosan concentration 1000mg/L; the PA/CS membrane so formed exhibited a permeation flux of 57.7L/(m2 h) and a salt rejection of 95.4% for a feed NaCl concentration of 1500mg/L at 0.8MPa. The PA/CS composite membrane also exhibited good performance for rejection of divalent salts (99.8% for MgCl2 and 98.5% for Na2SO4) at the same concentration. This modification technique is simple and practical because dilute solutions are used for surface treatment and commercial membrane units can be modified in their original modules. [Copyright &y& Elsevier]

Abstract: The technical feasibility of applying the bipolar membrane electrodialysis (BMED) to the production of the organic acid has been confirmed. However, some unsolved problems for BMED at present, such as high cost, instable properties and limited varieties for the bipolar membranes and even the poor permselectivity of the associated mono-polar membranes, make the explorations on other electrodialysis technologies for the production of the organic acid necessary. In this work, a resin-filling electrometathesis technology (EMT) is attempted to produce tartaric acid based on our previous work [Journal of Membrane Science 341 (2009) 246–251]. Similarly, the cell voltage, current efficiency and energy consumption are investigated and compared during the tartaric acid production by EMT before and after the filling of resin, respectively. The relevant experimental phenomena and potential mechanism are analyzed tentatively. Furthermore, the process economics, including the EMT and BMED before and after the filling of the acid resins, are all evaluated and compared. The preliminary results show that the modified EMT used for the tartaric production can be carried out at relatively higher current density with relatively lower energy consumption which effectively reduces the cost of operation and investment on the plant compared with the other technologies. [ABSTRACT FROM AUTHOR]

Abstract: Pretreatment to reverse osmosis (RO) seawater desalination historically has been achieved using organic (polymer) ultra- and micro-filter (UF/MF) membranes. Newly developed inorganic (ceramic) membranes offer unique advantages over the currently employed membranes, and were recently introduced for the purpose. In this work, we investigate the performance of a zirconium dioxide ceramic membrane with 0.05μm pore diameter to clarify raw seawater under different operating conditions. The influences of cross-flow velocity (2.7–4.9ms−1), temperature (15–55°C), transmembrane pressure (TMP) 0.1–0.2MPa, and seawater pH (5.5–9.5) on permeate flux and rejection were assessed. The results show that the zirconium dioxide membrane at cross-flow velocity of 3.7–4.2ms−1, TMP of 0.14–0.18MPa, temperature of 25–30°C and seawater pH of 8.0–9.0 exhibited a high flux of 420–450Lm−2 h−1 with turbidity and CODMn rejection of 99.0–99.5% and 32–35%, respectively. This work also introduces a new experimental procedure to determine different filtration resistance (R m, R sads, R pads, R cp, R pb and R cr) components, which helps the analysis of performance characteristics and the better understanding of interactions between the membrane and foulants. The present results show that the effect of concentration polarization was dominant in the ultrafiltration of raw seawater, and various fouling components contribute to the total in the order of R cp > R sr > R m > R sads > R pads > R irr. Further, reversible fouling was much more significant than irreversible fouling. The experimental method also showed interrelation between the reversible and irreversible resistances, whereby part of R sr is transformed into R irr within 20min of filtration. The results of this study indicate that zirconium dioxide ultrafiltration pretreatment before RO desalination can achieve consistent permeate quality and low fouling potential at high permeate fluxes. [Copyright &y& Elsevier]

Abstract: The kinetics of leaching selenium from Ni–Mo ore smelter dust in H2SO4-HCl-H2O system was investigated. The effects including leaching temperature and time, particle size of the smelting dust, stirring speed, acid concentration and the coefficient β (the molar ratio of sodium chlorate to selenium in the smelter dust) on leaching of selenium were studied. The results indicated that the leaching of selenium increased sharply with the increase of temperature. The leaching of selenium reached 98% at 95°C and stirring speed of 350rpm for 150min with the particle size of −0.15mm, initial [H+] concentration of 8mol/L, the solid/liquid ratio of 1:5g/mL and the coefficient β of 3.33. The leaching process was controlled by the surface chemical reaction and the kinetics of leaching selenium from Ni–Mo ore smelter dust followed the model of “shrinking core”. The apparent activation energy of leaching selenium was determined to be 44.4kJ/mol, which was consistent with the values of activation energy reported for the surface chemical reaction control. The kinetics equation of leaching selenium from Ni–Mo ore smelter dust was expressed as , which coincided with the experimental results. [Copyright &y& Elsevier]

Abstract: Interfacially polymerized polyamide thin film composite membrane was modified by electrostatic self-assembly of polyethyleneimine on the membrane surface, and the modified membrane showed significantly improved antifouling properties. The charge reversal on the membrane surface due to the application of the polyethyleneimine layer was shown to increase the fouling resistance of the membrane to cationic foulants because of the enhanced electrostatic repulsion, and the increased surface hydrophilicity would help minimize the flux reduction. The effects of parameters involved in the membrane surface modification (e.g., polyethyleneimine concentration and deposition time) on the membrane performance were investigated in terms of water permeation flux and salt rejection. The membrane modification was found to increase salt rejections when MgCl2 and NaCl were tested. The fouling behavior of the membranes was also studied with and without the presence of dodecyltrimethylammonium bromide (which is a common cationic surfactant present in waste water). It was shown that while the deposited polyethyleneimine surface layer tended to offer additional resistance to permeation, the improved fouling resistance and the increased surface hydrophilicity compensated for the reduction in membrane permeability due to the deposition of the polyethyleneimine layer. [Copyright &y& Elsevier]

Abstract: N,O-carboxymethyl chitosan (NOCC) composite nanofiltration membranes crosslinked by ECH were developed using a method of coating and crosslinking, where an epichlorohydrin/ethanol 96.7% (0.067 M KOH) solution was used as the crosslinking agent. The structure and the morphology of the resulting membrane were characterized by attenuated total reflection infrared spectroscopy (ATR-IR) and environmental scanning electron microscopy (ESEM). The effects of preparation conditions on the rejection performance of the resulting composite membrane were also investigated. At 20°C and 0.40 MPa the rejections of the resulting membrane to Na2SO4 and NaCl solutions (1000 mg L−1) were 90.4% and 27.4%, respectively, and the permeate fluxes were 7.9, and 10.8 kg m−2h−1, respectively. The rejections of this kind of NOCC/PSF composite NF membrane to the inorganic electrolyte solutions decreased in the order of Na2SO4, NaCl, MgSO4, and MgCl2. [Copyright &y& Elsevier]

Abstract: A copolymeric membrane material containing a tertiary amino group was synthesized by radical copolymerization of 2-(N,N-dimethyl amino) ethyl methacrylate and acrylonitrile. The chemical structure of the copolymer was analyzed by viscosity measurement, elemental analysis, FTIR and X-ray diffraction (XRD). The homogeneous copolymeric membrane was prepared. The sorption behavior as well as the permeation performance of the membranes for pure CO2 and CH4 were investigated. The results shown that CO2 sorption behavior of the membrane, which can be classified as a dual-mode sorption model, and CH4 sorption behavior of the membrane accord with the Fickian diffusion model. The membrane appears CO2 selective sorption preferentially, and facilitated transport caused by CO2 reacting reversibly with tertiary amino group for carrier in the membrane. [Copyright &y& Elsevier]

Abstract: N,O-carboxymethyl chitosan (NOCC) composite nanofiltration membranes having a polysulfone (PS) UF membrane as the substrate were prepared using a method of coating and cross-linking, in which a glutaraldehyde (GA) aqueous solution was used as the cross-linking agent. Attenuated total reflection infrared spectroscopy (ATR-IR) was employed to characterize the resulting membrane. The effects of the composition of the casting solution of the active layer, the concentration of the cross-linking agent, and the membrane preparation techniques on the performance of the composite membrane were investigated. At 13–15°C and 0.40MPa the rejections of the resulting membrane to Na2SO4 and NaCl solutions (1000mgL−1) were 92.7 and 30.2%, respectively, and the permeate fluxes were 3.0 and 5.1kgm−2 h−1, respectively. The rejection of this kind of membrane to the electrolyte solutions decreased in the order of Na2SO4, NaCl, MgSO4, and MgCl2. This suggests that the membrane active layer acquires a negative surface charge distribution by the adsorption of anions from the electrolyte solution and this charge distribution mainly determines the membrane performance. [Copyright &y& Elsevier]

Abstract: In this study, the chemical reaction between acetic acid (CH3COOH) used as non-solvent additive of casting solution and sodium carbonate (Na2CO3) dissolved in water as coagulant was employed to modify the classical phase inversion process. By means of this method, the polyethersulphone (PES) ultrafiltration (UF) membranes were prepared. The influence of acetic acid on the properties of the polymer solution was examined by viscometry and related to the morphology of the membrane prepared from the casting solution. The membranes were characterized in terms of the pure water flux, solute transport and field emission scanning electron microscope (FESEM) observation. It was found that chemical reaction between the additive and coagulant increases membrane permeability and mean pore size while maintaining the relatively narrow pore size distribution. FESEM images also confirmed that the chemical reaction contributes to suppress the formation of macrovoid and enhance the interconnectivity of pore. Furthermore, the potential mechanism of membrane formation influenced by chemical reaction was explored tentatively. [Copyright &y& Elsevier]

Cellulose triacetate (CTA) hollow fiber membrane for reverse osmosis (RO) desalination of brackish water with high salinity has been modified for pervaporation (PV) membrane of separating organic/organic mixture. The experiments presented that modified performance of CTA hollow fiber membrane treated by the organic solvent was affected by the modifying conditions. PV performance of CTA hollow fiber membrane modified mainly depends on the concentration of the modifying agent and the treatment time of CTA hollow fiber membrane in the aqueous acetone. The results showed that the membrane treated respectively by 5% acetone aqueous solution possesses a good PV separation performance, i.e. the separation factor 1998 and the permeate flux 45.1 (g/m2.h). It was exhibited from scanning electron microscope (SEM) photograph were produced. The structural changes from porous, defect to non-porous, even on the membrane surface and turn from asymmetric membrane of two layers consisting of the active and the support into the homogeneous membrane of single layer in the cross section of the membrane would indicated why the original RO membrane can become that of PV by means of modification treatment. [Copyright &y& Elsevier]

Macroporous substrates have great potential in the development of high performance thin film composite forward osmosis (TFC FO) membranes. This paper reports on the preparation of TFC FO membrane via support-free interfacial polymerization (SFIP) technology on a macroporous substrate. SFIP technology can effectively break the bottleneck of conventional interfacial polymerization (IP) technology, which makes it difficult to form a complete polyamide (PA) film on the macroporous substrate. Briefly, the complete PA film is formed at the free water-organic phase interface and then attached to the macroporous substrate by vacuum filtration. The monomer concentration and filtration pressure were adjusted to form the optimal SFIP-PA film. Meanwhile, we chose a macroporous polyvinylidene fluoride (PVDF) microfiltration substrate and screened the pore size to reduce the structural parameters and then the internal concentration polarization, which caused the improvement of water flux. The performance of SFIP-PVDF membranes was investigated and discussed. Under the AL-FS mode with DI water and 1.0 M NaCl solution as the feed solution and draw solution, respectively, the SFIP-PVDF membrane, which used a macroporous PVDF substrate with a pore size of 0.45 μm exhibited a water flux (20 L/m2·h) and a reverse salt flux (2.5 g/m2·h). Besides, the membrane showed good stability in the 72 h test. The specific salt flux (J s /J w) of SFIP-PVDF membranes was much lower than that of IP-PVDF membranes prepared via IP technology, which were incomplete and defective, suggesting that SFIP technology was superior to IP technology. This work effectively exploits the potential of macroporous substrates for the development of high performance TFC FO membranes and provides an insight into the high performance FO membrane design. [Display omitted] • Support-free interfacial polymerization (SFIP) technology was proposed to prepare FO membranes on macroporous substrates. • Macroporous substrates with a pore size of 0.45 μm had high porosity and low tortuosity. • Low ICP, high water flux, and low reverse salt flux were exhibited. • SFIP technology was superior to IP technology on macroporous substrates. [ABSTRACT FROM AUTHOR]

Thin film nanocomposite (TFN) organic solvent nanofiltration (OSN) membrane with improved separation performance was fabricated via interfacial polymerization reaction between amine-functionalized graphene quantum dots (af-GQDs) doped aqueous monomer solution of m -phenylenediamine (MPD) and n -hexane solution containing trimesoyl chloride (TMC) monomer. We emphasize the employment of extra-low content for both af-GQDs and MPD, so that we could maximize the function of these nanomaterials and eliminate their aggregation at the same time. The af-GQDs nanomaterials could regulate the interfacial polymerization process and could be strongly anchored in the polyamide film via covalent bonding, hence could prevent their loss while providing more channels for faster solvent penetration. As a result, the optimized OSN membrane, TFN-50, shows a super-smooth surface, with a surface roughness as low as 4.3 ± 0.2 nm, and excellent pure solvent permeances which reach 135.8, 112.7, and 69.8 L m−2 h−1 MPa−1 for methanol, DMF and ethanol, respectively, as well as a very high Rhodamine B (RDB, 479 Da) rejection of up to 99.2%, and an ethanol permeance of 61.4 L m−2 h−1 MPa−1. Furthermore, the TFN-50 OSN membrane still shows excellent filtration performance after being submerged in DMF for 336 h or continuous crossflow filtration with Rose bengal (RB, 1017 Da)/DMF solution for 136 h, demonstrating its excellent solvent resistance. [Display omitted] • TFN OSN membrane incorporated with af-GQDs nanomaterials is prepared via interfacial polymerization method. • Ultra-low content for af-GQDs and MPD is used in the aqueous phase during the interfacial polymerization process. • Af-GQDs effectively manipulate the interfacial polymerization process and help to form a selectivity layer with ultra-smooth surface. • Higher solvent permeance and excellent dye rejection performance are achieved with the aid of af-GQDs. • The af-GQDs doped OSN membrane has excellent durability performance in harsh strong polar solvents. [ABSTRACT FROM AUTHOR]

Novel acyl chloride monomer 5-(1-pyrrolidinyl)-1,3-benzenedicarbonyl dichloride (PIPC) featuring a rigid pyrrolidinyl group was proposed as an organic phase monomer to fabricate reverse osmosis (RO) membranes possessing exceptional water permeability and NaCl rejection via a two-step interfacial polymerization method. First, m -phenylenediamine (MPD) in the aqueous phase solution polymerized with PIPC in the first organic phase solution to form the much looser polyamide. After that the remaining MPD continued to diffuse to polymerize with trimesoyl chloride in the second organic phase solution to form the denser polyamide. The pyrrolidinyl group had steric hindrance effects and formed hydrogen bond with MPD, leading to decreasing the thickness significantly and increasing surface roughness of the separating layer. When the PIPC amount was 0.08 wt%, the PIPC-based RO membrane displayed optimal permselectivity with water flux increasing by 84.20 % compared to the original RO membrane (from 20.38 L·m−2·h−1 to 37.54 L·m−2·h−1) whereas retaining high NaCl rejection with 98.59 %. The PIPC-based RO membrane exhibited steady water flux and NaCl rejection within 120 h of filtration, as well as improved antifouling performance. Thus, preparation of the highly permeable RO membrane could be rationally achieved by the novel acyl chloride monomer with a rigid pyrrolidinyl group. [Display omitted] • The novel monomer PIPC was used to prepare RO membrane by a two-step IP method. • PIPC influenced the diffusion rate of MPD via hydrogen bonds and steric hindrance. • The PIPC-based membrane presented rougher surface and thinner PA layer. • Permeability of PIPC-based membrane was obviously enhanced without losing NaCl rejection. [ABSTRACT FROM AUTHOR]

To effectively separate Mg2+ and Li+ from high Mg2+/Li+ ratio salt lake brine, positively charged thin film composite polyamide (TFC-PA) nanofiltration (NF) membranes were prepared by the interface polymerization involving polyethyleneimine (PEI) with benzenetricarbonyl chloride (TMC). In this work, the structures and performances of PEI based TFC-PA NF membrane prepared on polysulfone (PSF) ultrafiltration substrates from the normal interface polymerization process PSF(NIP), was compared with those on the same substrates from the reverse-phase interface polymerization (RIP) process PSF(RIP), and those on polyethylene substrates from RIP process PE(RIP). Results showed that PSF(RIP) showed improved Mg2+/Li+ separation factor S Li/Mg from PSF(NIP) with an increased surface positive charge, but with greatly reduced water flux values due to reduced surface roughness, increased surface hydrophobicity, and decreased MWCO Stokes pore radius. PE(RIP) NF membrane showed not only higher Mg2+/Li+ separation factor S Li/Mg , but also higher water flux values due to increased surface roughness, decreased PA cross-linking degree, reduced PA separation layer thickness, and increased MWCO Stokes pore radius. PE(RIP) NF membrane also showed high rejection rates to a variety of divalent metal salts with high separation factors S Li/Mg of 40–49, high brine permeability values of 10.5 L·m−2·h−1·bar−1, and excellent chemical and operational stability. PEI based TFC-PA NF membranes with positive surface charges on varied substrates and interface polymerization methods were prepared. Novel PE(RIP) NF membranes made from lower cost PE based substrates, showed high brine flux values of 10.5 L·m−2·h−1·bar−1, >97 % rejection rates to variety of divalent metal salts, high Mg2+/Li+ separation factors S Li/Mg of 40–49. [Display omitted] • PEI based TFC-PA NF membranes with positive charges were prepared; • Impact from substrates and IP methods on Mg2+/Li+ separation of positive NF membranes studied; • PE(RIP) NF membranes showed high flux (10.5 L·m−2·h−1·bar−1), high Mg2+/Li+ separation factors (40–49) and excellent chemical and operational stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • DETA/TA cross-linked polymeric substrate was first used to fabricate dense MOF membrane. • TA and DETA provided enough heterogeneous sites for preparing dense MOF membrane. • DETA anchored TA molecules on hollow fiber substrate to form tight spatial network. • Structure stability of membrane was enhanced by the synergistic effect between TA and DETA. • TA-DETA-PVDF/ZIF-8 composite membrane showed considerable gas separation performance. In this work, a continuous dense zeolite imidazolate framework (ZIF) composite membranes for enhanced gas separation were successfully prepared on diethylenetriamine (DETA) and tannic acid (TA) cross-linked polymeric hollow fiber substrates via the in-situ solvothermal method for the first time. With strong reactivity and small molecular volume, DETA connected various TA molecules and anchored TA molecules on the organic hollow fiber substrate to form a relatively tight spatial network. The modified polyvinylidene fluoride(PVDF) support contained abundant phenolic hydroxyl, carbonyl, and amine groups, providing a large number of active sites for heterogeneous nucleation and promoting the forming of continuous and non-defect MOF film. The synergistic effect between TA and DETA not only enhanced the stiffness and durability of the MOF composite membrane, but also improved the performance of membrane on gas separation. The morphology of the amine/TA modified to support and the MOFs composite membrane was analyzed by SEM, XRD, FTIR, XPS, etc. The fabricated TA-DETA-PVDF/ZIF-8 composite membrane with a continuously dense layer and unique structural stability displayed excellent H 2 permeance of 1.01 × 10-7 mol·m−2 s−1 Pa−1 and competitive H 2 /N 2 and H 2 /CH 4 selectivity of 24.0 and 24.4, respectively. [ABSTRACT FROM AUTHOR]

PEI/ZIF TFC total heat exchange membranes (THEMs) with enhanced energy recovery and CO 2 barrier properties were formed by in situ grown ZIL-L micro crystalline leaves from the PEI matrix. PEI sealing could effectively open up internal pores of ZIF-L particles while shapes of ZIF-L could be tuned further for better THEM performance. [Display omitted] • PEI chains could tightly seal a mass of ZIF-L on PSF substrates. • PEI sealing could effectively open up internal pores of ZIF-L particles. • Large masses of ZIF-L particles were well dispersed in the PEI matrix. • Shapes of ZIF-L could be tuned for better THEM performance. • THEMs with higher energy recovery and CO 2 barrier properties were formed. A novel strategy was developed to build high-performance thin film composite (TFC) total heat exchange membranes (THEMs) by in situ growing ZIF-8 crystalline micro-leaves (ZIF-L) from Polyethyleneimine (PEI) coated on polysulfone (PSF) ultra-filtration substrates. It was found that flexible PEI polymeric chains could tightly cross-link and seal large masses of ZIF-L micro-leaves (ZIF/PEI wt. ratio up to 18.5) to thwart CO 2 permeation, on top of PSF substrate. Such PEI cross-linking could also effectively open up the internal channels of ZIF-L micro-leaves to enhance moisture permeance and latent heat recovery without trading off CO 2 gas barring property. ZIF-L in varied shapes protruded into the air stream could provide ultra-rough surfaces with increased surface area for improved total energy recovery efficiency. Optimized PEI/ZIF-L TFC THEMs showed ultra-low CO 2 permeance of 0.5–8 GPU and ultra-high total heat recovery rates of 68–74%. [ABSTRACT FROM AUTHOR]

• A framework for instance disambiguation with context awareness is proposed. • A method of correlation calculation based on corpus and knowledge is presented. • The priorities of contextual terms in different locations are identified. • The experiments for disambiguation based on ground-truth datasets are conducted. Conceptualization is to obtain the most appropriate concepts for noun terms (entities) under different contexts, which plays an important role in human knowledge understanding. However, in natural language, entities are often ambiguous, which creates difficulties in conceptualization. To accurately conceptualize, we must eliminate the ambiguity of entities. Existing methods mainly rely on similar or related entities in context for disambiguation. However, due to the sparsity of user-generated short texts, the number of entities that can be extracted from them is limited. In this paper, we propose an entity disambiguation method, which consists of three steps. (1) Measuring the correlation between terms, which uses both corpus and knowledge information to capture the specific semantic relationship. (2) Selecting informative terms, which considers various types of contextual terms, not just entities, thereby mitigating the effects of text sparsity. (3) Prioritizing informative terms to highlight their discriminative power, which reduces noise interference. Finally, the target entity is disambiguated based on informative terms. Experimental results on ground-truth datasets demonstrate that the proposed method outperforms baseline methods. [ABSTRACT FROM AUTHOR]